Table 2.
Baseline Characteristics of Patient Population in Wave 2, by Randomization Arm
| Characteristics | Mailed warning postcard (n = 1723) |
Mailed encouraging postcard (n = 1750) |
Standardized mean differencesa |
|---|---|---|---|
| Demographic characteristics | |||
| Age, median [IQR], years | 70.9 [65.7, 76.9] | 70.7 [64.8, 76.7] | 0.050 |
| Male sex, n (%) | 1687 (97.9%) | 1711 (97.8%) | 0.002 |
| Race, n (%) b | 0.014 | ||
| American Indian or Alaska native | 13 (0.8%) | 13 (0.7%) | |
| Asian | 8 (0.5%) | 7 (0.4%) | |
| Black | 289 (16.8%) | 296 (16.9%) | |
| Native Hawaiian or other Pacific Islander | 10 (0.6%) | 9 (0.5%) | |
| White | 1301 (75.5%) | 1321 (75.5%) | |
| Ethnicity, n (%)b | 0.026 | ||
| Hispanic/Latinx | 64 (3.7%) | 57 (3.3%) | |
| Not Hispanic/Latinx | 1596 (92.6%) | 1638 (93.6%) | |
| Geographic region, n (%)b,c | 0.028 | ||
| Northeast | 179 (10.4%) | 192 (11.0%) | |
| Midwest | 402 (23.3%) | 394 (22.5%) | |
| South | 825 (47.9%) | 832 (47.5%) | |
| West | 316 (18.3%) | 331 (18.9%) | |
| Rural residence, n (%)b | 654 (38.0%) | 681 (38.9%) | 0.020 |
| Marital status, n (%)b | 0.063 | ||
| Married | 839 (48.7%) | 892 (51.0%) | |
| Divorced/separated | 573 (33.3%) | 576 (32.9%) | |
| Never married/single | 142 (8.2%) | 119 (6.8%) | |
| Widow/widower | 163 (9.5%) | 160 (9.1%) | |
| Co-morbidities, n (%) | |||
| Coronary artery disease | 1363 (79.1%) | 1399 (79.9%) | 0.021 |
| Heart failure | 1281 (74.3%) | 1300 (74.3%) | 0.001 |
| Atrial fibrillation | 1015 (58.9%) | 1029 (58.8%) | 0.002 |
| Stroke | 312 (18.1%) | 329 (18.8%) | 0.018 |
| Dementia | 211 (12.2%) | 213 (12.2%) | 0.002 |
| Depression | 670 (38.9%) | 712 (40.7%) | 0.037 |
| Post-traumatic stress disorder | 360 (20.9%) | 383 (21.9%) | 0.024 |
| Alcohol use disorder | 226 (13.1%) | 210 (12.0%) | 0.034 |
| Cancer | 352 (20.4%) | 367 (21.0%) | 0.013 |
| Pacemaker or ICD characteristics | |||
| Device type, n (%) | 0.051 | ||
| Pacemaker | 684 (39.7%) | 652 (37.3%) | |
| ICD | 1039 (60.3%) | 1098 (62.7%) | |
| Prior pacemaker or ICD care | |||
| In-person device interrogation in past 1 year, n (%) | 1032 (59.9%) | 976 (55.8%) | 0.084 |
| Time since device placement, median [IQR], years | 3.24 [1.63, 5.47] | 3.43 [1.73, 5.64] | 0.086 |
| Time since last transmission, median [IQR], days | 177 [140, 312] | 184 [141, 346] | 0.012 |
| Generator manufacturer, n (%) | 0.043 | ||
| Abbott | 452 (26.2%) | 460 (26.3%) | |
| Biotronik | 120 (7.0%) | 107 (6.1%) | |
| Boston Scientific | 365 (21.2%) | 360 (20.6%) | |
| Medtronic | 786 (45.6%) | 823 (47.0%) | |
IQR interquartile range, ICD implantable cardioverter-defibrillator
aStandardized mean differences between encouraging vs. warning postcard arms in wave 2. A value < 0.1 denotes successful randomization
bTotals may not equal 100% because of the following numbers of unknown or missing variables: sex (n = 2), race (n = 206), ethnicity (n = 118), region (n = 2), rural (n = 1), and marital status (n = 9)
cStates by region: Northeast (Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, Vermont, New Jersey, New York, Pennsylvania), Midwest (Illinois, Indiana, Michigan, Ohio, Wisconsin, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, South Dakota), South (Delaware, District of Columbia, Florida, Georgia, Maryland, North Carolina, South Carolina, Virginia, West Virginia, Alabama, Kentucky, Mississippi, Tennessee, Arkansas, Louisiana, Oklahoma, Texas), West (Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, Wyoming, Alaska, California, Hawaii, Oregon, Washington)